In the windswept British seaside town of Ridinghouse Bay, single mom Alice Lake finds a man sitting on a beach outside her house. He has no name, no jacket, and no idea how he got there. Against her better judgment, she invites him inside. Meanwhile, in a suburb of London, newlywed Lily Monrose grows anxious when her husband fails to return home from work one night. Soon, she receives even worse news: according to the police, the man she married never even existed.